1. Field of the Invention:
The present invention relates to engine ignition and charging systems, such as for gasoline engines employing spark plugs. More particularly, the present invention relates to marine engine ignition and charging systems.
2. Description of the Prior Art:
It is known in small engine ignition systems to provide trigger coils which sense passage of a magnet or magnetic flux and which generate a trigger signal. A magnetic flux path may be generated by a ring magnet and associated flux concentrator plates, the flux path being sensed by the trigger coils. The trigger signals may be employed to produce ignition pulses, such as by a capacitive discharge ignition circuit controlled by the trigger signals. Exemplary of such systems are U.S. Pat. Nos. 3,741,185 and 3,961,618 and certain prior art alternators such as by the Suzuki Corp.
With such prior art systems, the trigger pulses from the pickup or trigger coils are dependent on RPM. At low RPM, slow flux changes result in weak output pulses from the trigger or pickup coils. Furthermore, at low RPM, the shape of the trigger pulses is different than at higher RPMs. The change in amplitude and shape of the trigger pulses causes various problems in such prior art ignition systems. For example, at low RPM, the engine may not start due to insufficient trigger signal amplitude or improper wave shape. Furthermore, the ignition timing changes from low to high RPM in view of the pulse amplitude and shape variations. Thus, complicated circuitry is required to take into account the changing ignition timing with variations in speed. Also, with such prior art systems, ignition timing adjustments can be complicated and cannot be optimized.
It has also been known in prior art systems such as in the Chrysler Hall effect device gasoline engine distributor shown at page 76 of the Micro Switch, Honeywell Division Catalog No. 20, issue 7, 1984, to provide a single Hall effect device having a construction such as shown at page 25 of the Micro Switch catalog, wherein such a device is mounted alongside a rotating distributor shaft and wherein a ferrous metal vane-interrupter as part of the rotor assembly is provided. The individual vanes, pass through a gap between a magnet and a Hall effect sensor so as to switch the Hall effect sensor on and off. In such a system, power for the Hall effect device is supplied directly from a battery associated with the gasoline engine.
The above described Hall effect device triggers the ignition module in a fashion analogous to a breaker type ("points") Kettering ignition system. Thus, the Hall effect device with its associated circuitry is a substitute for the points and forms a breakerless conductive ignition system.
With such a prior art system, the Hall effect devices require the vehicle battery for power, and the battery must be disconnected from the Hall effect devices and associated circuitry when the engine is not running. Furthermore, in such a prior art system a distributor, rotor, and distributor cap is required. Furthermore, since only one Hall effect device is used for all cylinders, if a defect occurs, timing to all cylinders is affected adversely so that ignition to all cylinders is affected.
It has also been known, such as shown at page 76 of the Micro Switch catalog, to provide a ring magnet with alternating poles for alternating on/off actuation of a Hall effect device.
An additional problem of prior art systems is the creation of radio frequency interference (RFI).
A further problem in prior art ignition and/or charging systems is a continuing battery drain, though perhaps small, even when the engine is not running. Such prior art systems thus required a battery disconnect switch.